Although aggression among girls was once thought to be relatively rare, more recent research suggests that girls frequently engage in relational aggression (e.g., manipulating relationships and social standing through gossip and social exclusion). Despite advances in understanding relational aggression and its repercussions, almost all aggression intervention efforts have been designed for physical aggression and for boys. Further, given the increased risk experienced by African American students in inner-city, under-resourced areas, strategies for building the capacity of inner-city schools to promote high-risk girls'productive social problem solving skills while decreasing their levels of relational and physical aggression are critically needed. With funding from NIMH (K23 Award), the principal investigator has designed a 20 session school-based group intervention, called Friend to Friend (F2F). The goal of F2F is to teach 3rd-5th grade inner-city African American relationally aggressive girls social problem-solving skills and reduce their levels of aggression. In the K23 Award, relationally aggressive girls from two inner-city schools participating in F2F were compared to relationally aggressive girls in a no treatment control condition. Results were extremely promising and were used to establish effect size estimates for the planning of a clinical trial. The proposed trial will examine program impact across six inner-city elementary schools, a wider range of outcome measures, and will use a more sophisticated research design by comparing F2F to a psychoeducational attention control group. Further, the trial will explore the relation between girls'social problem solving skills and relationally aggressive behaviors, whether positive changes are maintained at 9 month follow-up, and whether F2F has an impact upon broader indicators of school safety, psychological adjustment, and school performance. Relevance: Aggression among today's youth has been documented as one of society's most costly problems, and recent research suggests relational aggression may be associated with later internalizing and externalizing disorders among girls. As such, developing early interventions for relationally aggressive girls may help to reduce serious mental health disorders later in life.